How do get rid of large numbers of duplicate transactions

The Community has you covered, @tkmets. I can share easy steps so you can remove those duplicate transactions.

In QuickBooks Self-Employed, excluding transactions is one of the ways to remove duplicates. To do so, please refer to the steps below:

1. Go to the Transactions menu.
2. Check the box of the duplicate transactions.
3. Then, click the Exclude icon. 
4. Hit Apply. 

Excluding transactions are for those downloaded from your bank. For those transactions you added manually, you can delete them in QuickBooks. Here's how:

1. Navigate to the Transactions menu.
2. Find the transaction you want to delete.
3. Select the Delete icon.
4. Then Apply.  

Here's the article that will provide more info about the process: Handle duplicate transactions in QuickBooks Self-Employed.

Then, to ensure that your transactions are organized and match the correct line on your Schedule C form, you may visit this article for more details: Categorise transactions in QuickBooks Self-Employed.

Should you need anything else, don't hesitate to comment below. I'm always around to help if you have further concerns about removing duplicate transactions in QBSE. Stay safe and take care always.